go/typesパッケージを使い変数名をリネームしてみる #golang ref: http://qiita.com/tenntenn/items/beea3bd019ba92b4d62a

file0.txt

$ golang.org/x/tools/cmd/gorename

file1.go

fset := token.NewFileSet()
f, err := parser.ParseFile(fset, "sample.go", src, 0)
if err != nil {
    log.Fatalln("Error:", err)
}

file10.go

package main

var msg = "hoge"

func main() {
    msg := "Hello,"
    msg += " World"
    println(msg)
}

file2.go

package main

func main() {
    msg := "Hello,"
    msg += " World"
    println(msg)
}

file3.go

// 47バイト目 = msg
const p = 47
var pos token.Pos
fset.Iterate(func(f *token.File) bool {
    if f.Name() == "sample.go" {
        pos = f.Pos(p)
        return false
    }
    return true
})

file4.go

var ident *ast.Ident
ast.Inspect(f, func(n ast.Node) bool {
    if n == nil || pos < n.Pos() || pos > n.End() {
        return true
    }

    if n, ok := n.(*ast.Ident); ok {
        ident = n
        return false
    }

    return true
})

file5.go

conf := &types.Config{
    Importer: importer.Default(),
}

info := &types.Info{
    Defs: map[*ast.Ident]types.Object{},
    Uses: map[*ast.Ident]types.Object{},
}

_, err = conf.Check("main", fset, []*ast.File{f}, info)
if err != nil {
    log.Fatalln("Error:", err)
}

file6.go

type Object interface {
        Parent() *Scope // scope in which this object is declared
        Pos() token.Pos // position of object identifier in declaration
        Pkg() *Package  // nil for objects in the Universe scope and labels
        Name() string   // package local object name
        Type() Type     // object type
        Exported() bool // reports whether the name starts with a capital letter
        Id() string     // object id (see Id below)

        // String returns a human-readable string of the object.
        String() string
        // contains filtered or unexported methods
}

file7.go

from := ident.Name
const to = "message"
fmt.Println(ident, "->", to)

obj := info.Defs[ident]
if obj == nil {
    obj = info.Uses[ident]
}

// Defs
fmt.Println("== Defs ==")
for i, o := range info.Defs {
    if i.Name == from && o.Parent() == obj.Parent() {
        fmt.Println(fset.Position(i.Pos()))
        i.Name = to
    }
}

// Uses
fmt.Println("== Uses ==")
for i, o := range info.Uses {
    if i.Name == from && o.Parent() == obj.Parent() {
        fmt.Println(fset.Position(i.Pos()))
        i.Name = to
    }
}

file8.go

package main

import (
    "fmt"
    "go/ast"
    "go/format"
    "go/importer"
    "go/parser"
    "go/token"
    "go/types"
    "log"
    "os"
)

// sample.go
const src = `package main

func main() {
    msg := "Hello,"
    msg += " World"
    println(msg)
}`

func main() {
    fset := token.NewFileSet()
    f, err := parser.ParseFile(fset, "sample.go", src, 0)
    if err != nil {
        log.Fatalln("Error:", err)
    }

    conf := &types.Config{
        Importer: importer.Default(),
    }

    info := &types.Info{
        Defs: map[*ast.Ident]types.Object{},
        Uses: map[*ast.Ident]types.Object{},
    }

    _, err = conf.Check("main", fset, []*ast.File{f}, info)
    if err != nil {
        log.Fatalln("Error:", err)
    }

    // 47バイト目 = msg
    const p = 47
    var pos token.Pos
    fset.Iterate(func(f *token.File) bool {
        if f.Name() == "sample.go" {
            pos = f.Pos(p)
            return false
        }
        return true
    })

    var ident *ast.Ident
    ast.Inspect(f, func(n ast.Node) bool {
        if n == nil || pos < n.Pos() || pos > n.End() {
            return true
        }

        if n, ok := n.(*ast.Ident); ok {
            ident = n
            return false
        }

        return true
    })

    from := ident.Name
    const to = "message"
    fmt.Println(ident, "->", to)

    obj := info.Defs[ident]
    if obj == nil {
        obj = info.Uses[ident]
    }

    // Defs
    fmt.Println("== Defs ==")
    for i, o := range info.Defs {
        if i.Name == from && o.Parent() == obj.Parent() {
            fmt.Println(fset.Position(i.Pos()))
            i.Name = to
        }
    }

    // Uses
    fmt.Println("== Uses ==")
    for i, o := range info.Uses {
        if i.Name == from && o.Parent() == obj.Parent() {
            fmt.Println(fset.Position(i.Pos()))
            i.Name = to
        }
    }

    fmt.Println()
    fmt.Println("==== Before ====")
    fmt.Println(src)

    fmt.Println()
    fmt.Println("==== After ====")
    format.Node(os.Stdout, fset, f)
}

実行結果

msg -> message
== Defs ==
sample.go:6:2
== Uses ==
sample.go:7:2
sample.go:8:10

==== Before ====
package main

var msg = "hoge"

func main() {
    msg := "Hello,"
    msg += " World"
    println(msg)
}

==== After ====
package main

var msg = "hoge"

func main() {
    message := "Hello,"
    message += " World"
    println(message)
}